Resistant Identification And Genotype Analysis Of Several Rice Varieties To Blast In Jiangsu Area

In the present study, resistance of four sets of rice varieties (Chinese race differentials, Tsunematru mono-resistance gene lines from Japan, Lijiangxintuanheigu from CAAS and C039 near isogenic lines from IRRI) were studied with 19 strains of M. griseas in Jiangsu area by using artificial inoculation. The correlation between seedling blast and neck blast was studied, and the virulence of M. griseas in Jiangsu area currently was detected. Meanwhile, according to characteristics of M. griseas, a new set of differential varieties which was suitable for Jiangsu area was proposed. Then, nine varieties which have known resistant genes, and nine varieties released in Jiangsu area were inoculated with the 19 strains of M. griseas at booting stage. Those varieties were detected with 9 pairs of markers linked with resistant genes. Based on those works, genotypes of rice varieties in Jiangsu area were analyzed, and a program for rice improvement was also proposed.1 Identification of resistance to blast of rice varietiesIn this study, resistance of 51 varieties, including four sets of blast differential varieties, nine rice varieties which have known resistant genes, and nine rice varieties released in Jiangsu area were studied with 19 strains of M. griseas. Results showed that a great difference of resistant ability to rice blast was existed among those varieties, and the frequency was ranged in 0-100%. By using 33 varieties, seedling and booting inoculation were carried out, and the correlation coefficient between seedling blast and booting blast was shown significant at 0.01 level (r=0.599,p0.01=0.428), which validated that, booting blast could be deduced by seedling blast.2 Virulence of main races in Jiangsu areaThe study analyzed the reaction of 33 rice varieties to blast at different growth stages, and calculated the pathogenic ratio of different races of M. griseas. Results showed that ZD1 and ZF1 races had stronger virulence than others in Jiangsu area. Especially for ZF1 race, all strains selected from ZF1 race had highly pathogenic frequence to four sets rice varieties.3 Suitable differential varieties to identify M. griseas in Jiangsu areaThe reaction of rice lines from Tsunematru mono-resistance gene lines (TMGLs) to M. griseas had notable difference, and so did of Lijiangxintuanheigu near isogenic lines (LTH NILs). Both of them had clear resistant genes and genetic background. The varieties belong to LTH NILs had monotonous identification to ZF1 and ZG1 races, and showed high resistance to ZE3 race, while, high sensitivity to ZD3 race. Reaction of Aichiasahi, K3, Fukunishiki and K59 to M. griseas was complementary with LTH NILs. According to the characteristics of M. griseas and rice variety in Jiangsu area, LTH NILs and four rices of TMGLs (Aichiasahi, K3, Fukunishiki and K59) might be suitable differential varieties to M. griseas in Jiangsu area.4 Resistant genotyping to rice blast of several rice varietiesNine rice varieties which have known resistant genes, and some rice varieties released in Jiangsu area were inoculated 19 strains of M. griseas at booting stage, and genotype was analyzed with linked markers of resistant genes. Results showed, those varieties could be divided into two categories by clustering based on molecular amplification, and tended to the division of indica and japonica subspecies.Japonica rice in Jiangsu area had differential resistance to blast. For example, Changshujing had resistance to G1 strain, but others showed sensitivity; H6P357 had resistance to F1, F2 strains, but Nanjing 44, Nanjing 45 and Nanjing 46 were sensitivity. Molecular test also showed different bands among such varieties, and there was certain complementarity each other. For example, Nanjing varieties had not part bands that showed in Changshujing, Ningjing No.1 and Tetep. The results provided the theoretical basis for conducting multi-genic pyramiding to breed rice variety with wide resistant ability to rice blast in Jiangsu area.5 Breeding strategy based on resistant identification and genotype analysisFor rice varieties in Jiangsu area, the main pathogenic strains were G1, F1～F4, and C1. Gumei No 4, Digu and Tetep had resistance to 19 strains collected from Jiangsu area. The three varieties provided high-quality resistant source for rice breeding in Jiangsu area, and theoretical foundation for rice improvement and breeding of disease-resistant. Nanjing varieties could be improved by taking advantage of Gumei No.4 and C039, while, other test-varieties could be improved by using Digu, Tetep and C039.